Semiconductor apparatus and process of production thereof

ABSTRACT

A method of producing a semiconductor apparatus, the method including forming metal ball bumps in direct contact with a circuit pattern of a semiconductor device, forming a resin film to seal spaces between the metal ball bumps, cleaning the surfaces of the metal ball bumps projecting out from the resin film using plasma cleaning by removing components inviting a rise in a connection resistance and a decline in a joint strength, forming eutectic solder layers different in composition from the metal ball bumps on the surfaces of the metal ball bumps, cutting the semiconductor substrate into unit semiconductor chips, and mounting at least one of the chips on a mounting board from a bump forming surface side of the chip so as to connect the eutectic solder layers to the mounting board with the resin film directly contacting the chip and not directly contacting the mounting board.

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.09/385,959 filed on Aug. 30, 1999, the entirety of which is incorporatedherein by reference to the extent permitted by law. The presentapplication claims the benefit of priority to Japanese PatentApplication No. 10-247393 filed in the Japanese Patent Office on Sep. 1,1998 and Japanese Patent Application No. 11-146942 filed in the JapanesePatent office on May 26, 1999. The entire contents both of which areincorporated herein by reference to the extent permitted by law.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor apparatus mounted usingsolder or other metal bumps and a process of production of the same.

2. Description of the Related Art

In recent years, digital video cameras, digital cellular phones,notebook-type personal computers, and other portable electronicequipment have spread widely. There are mounting demands for reducingthe size, reducing the thickness, and reducing the weight of theseportable electronic equipment.

To realize this reduction in size, reduction in thickness, and reductionin weight of portable electronic equipment, the most important issue isthe improvement of the mounting density of the components.

In particular, even in semiconductor ICs and other semiconductordevices, high density mounting technology using flip-chip-typesemiconductor devices instead of the package-type semiconductor devicesof the related art is being developed and put into practical use.

In the past, as the form of packaging of semiconductor apparatuses, useDIP (Dual Inline Package) or PGA (Pin Grid Array) have been used as wellas other through hole mounted devices (THD) mounted to printed circuitboards by inserting leads through holes provided there and QFP (QuadFlat (L-Leaded) Package) or TCP (Tape Carrier Package) or other surfacemounted devices (SMD) mounted by soldering leads to the surfaces of theboards.

To further reduce sizes, attention has focused on the method of mountinga semiconductor chip with its pad opening surface facing the mountingboard by a package called a chip size package (CSP, also called a FBGA(Fine-Pitch BGA)) for realizing further smaller sizes and higherdensities to bring the package size extremely close to the size of thesemiconductor chip (flip-chip mounting). Active research has beenconducted up until now and numerous proposals have been made.

One of the mounting methods for mounting such a flip-chip typesemiconductor device (flip-chip mounting) is for example the method offorming for example spherically shaped (ball shaped) solder bumps(solder ball bumps) on electrode pads comprised of aluminum (Al) etc. ofa semiconductor IC and bringing the connection terminals of thesemiconductor IC into contact with the solder ball bumps to directlymount the IC chip on a printed circuit board.

A semiconductor apparatus comprised of a CSP type semiconductor chipmounted on a mounting board will be explained with reference to thedrawings.

FIG. 11 is a sectional view of the above semiconductor apparatus.

The surface of the semiconductor device (semiconductor wafer) 10 onwhich electrode pads 11 comprised of Al etc. are formed is covered forexample by a first surface protective film 12 comprised of a siliconnitride layer and a second surface protective film 13 comprised of apolyimide layer in a state leaving only the electrode pad 11 portionsopen. Further, a conductive film 14 comprised of a stacked films ofchrome (Cr), copper (Cu), gold (Au), etc. is formed at the openings ofthe electrode pad 11 portions to be connected to the electrode pads 11.The conductive film is sometimes called a BLM (Ball Limiting Metal)film.

Further, solder bumps 16 b comprised of for example high melting pointsolder balls are formed connected to the conductive film (BLM film) 14.

A CSP type semiconductor chip 1 is constituted in this way.

On the other hand, the mounting board 2 is a board 20 comprised of forexample a glass epoxy-based material on the top of which are providedlands (electrodes) 21 formed at positions corresponding to the positionsof formation of the solder bumps 16 b of the semiconductor chip 1 to bemounted and comprised of copper etc. and a not shown printed circuitconnected to the lands 21 and formed on the front surface or backsurface or the two surfaces of the board 20. The surface of the board 20other than the land 21 portions is covered by a solder resist 23.

The above CSP type semiconductor chip 1 is mounted on the mounting board2 with the bumps 16 b aligned with the lands 21. The bumps 16 b andlands 21 are mechanically and electrically connected by eutectic solderlayers 19.

Further, the space between the CSP type semiconductor chip 1 andmounting board 2 is sealed by a sealing resin 3 comprised of an epoxyresin etc.

In the above semiconductor apparatus, as the method of forming the bumpsat predetermined positions, for example there is known the method ofusing electrolytic plating. In this case, there is the disadvantage thatthe thickness of the solder bumps formed is affected by the surfaceconditions of the layer of material forming the underlayer of the bumpsor the slight variation in the electrical resistance and that theformation of uniform solder bumps of the same height in a semiconductorchip is extremely difficult.

Therefore, a method is being developed for formation of solder ballbumps with a uniform height using formation of a solder film by vacuumdeposition and lift-off of the photoresist layer.

This method will be explained below with reference to the drawings.

First, as shown in FIG. 12A, electrode pads 11 comprised of an aluminum(Al) and copper (Cu) alloy etc. are formed by patterning on asemiconductor wafer 10 formed with circuit patterns of semiconductorchips by for example the sputtering method or etching etc. and a surfaceprotective film 13 comprised of for example a silicon nitride layer orpolyimide layer etc. is formed on top of it covering the entire surface.

The electrode pad 11 portions of the surface protective layer 13 areopened, then for example a pattern is formed by the sputtering method soas to connect a conductive layer (BLM layer) 14 comprised of a stackedfilm of chrome, copper, and gold to the electrode pads 11.

Next, as shown in FIG. 12B, a resist film R2 having pattern openings Pis formed by patterning at the conductive film (BLM film) 14 formingareas by a photolithography step.

Next, as shown in FIG. 12C, solder layers 16 are formed in the patternopenings P of the resist film R2 by forming a solder layer over theentire surface by for example a vacuum evaporation method. At this time,solder layers 16 a are formed over the resist film R2 as well.

Next, as shown in FIG. 13A, the solder layers 16 a formed over theresist film R2 are simultaneously removed by removing the resist film R2by lift-off. Due to this, it is possible to leave only the solder layers16 formed in the pattern openings P of the resist film R2.

Next, as shown in FIG. 13B, heat treatment is performed to make thesolder layers 16 melt. These are cooled and solidified in a stateforming spheres due to the surface tension so as to form solder ballbumps 16 b.

As explained above, the solder ball bumps 16 b are formed in thesemiconductor wafer state (that is, the state before being cut intoindividual semiconductor chips).

The semiconductor wafer formed with the solder ball bumps 16 b in thisway is cut by dicing etc. into individual semiconductor chips, then asshown in FIG. 11, the solder ball bumps 16 b are made to abut againstthe lands 21 comprised of Cu etc. formed on the board 20 of the mountingboard 2.

Here, the board 20 is covered by a solder resist 23 over its entirefront surface except for the lands 21 and is precoated by a eutecticsolder layer 19 over the areas of the lands 21 or the surfaces of thesolder ball bumps 16 b.

Therefore, using a reflow step, the eutectic solder 19 is melted and themelted eutectic solder enters between the solder ball bumps 16 b andlands 21. By cooling and hardening it, the solder ball bumps 16 b aresoldered and electrically connected to the lands 21.

The thermal stress becomes a major disadvantage for the reliability ofthe joint by the bumps after flip-chip mounting due to the differencesin the coefficients of heat expansion of the semiconductor chips and themounting board (printed circuit board).

While the coefficient of heat expansion of silicon is 3.4 ppm/° C., thecoefficient of heat expansion of the generally widely used glassepoxy-based mounting board is a large about 15 ppm/° C. When thermalstress is repeatedly applied to bump joints by the temperaturedifference caused by the on/off operation of a chip, cracks are causedin the joints and breakage or malfunctions are caused in some cases.

To deal with the above disadvantage, as shown in FIG. 11, the method isgenerally adopted of injecting a sealing resin 3 between thesemiconductor chips 1 and mounting board 2 and relieving the thermalstress applied to the weak strength bump joints by having the stress ofheat expansion received by the sealing resin as a whole.

In the above flip-chip mounting method of the related art, however,since the semiconductor chips and the mounting board are secured by asealing resin, when a defect occurs in a device chip, the only methodwas to discard the entire mounting board 2 on which that semiconductorchip 1 was mounted or apply a chemical or mechanical external force toforcibly tear off that semiconductor chip.

Here, the replacement of the entire mounting board 2 of the former casehas the disadvantage of the cost ending up higher, while the forciblytearing off of the semiconductor chip 1 of the latter case ends updamaging the mounting board 2.

Therefore, the work of replacing a defective component in the case of adefect occurring in a semiconductor chip 1, that is, the so-calledrework, is difficult. This has become one factor behind the failure offlip-chip mounting from spreading widely.

Further, along with the reduction of pitch accompanying the reduction ofsize of semiconductor devices, at the time of injection of the sealingresin, the circulation of the sealing resin 3 becomes poor and fullinjection of the sealing resin 3 can no longer be achieved, so there isalso the disadvantage that the thermal stress cannot be sufficientlyrelieved.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a semiconductorapparatus and a process of production thereof which enable the thermalstress between a semiconductor device and mounting board to be reliablyrelieved without the use of a sealing resin and further which can reducethe connection resistance and can increase the strength of the jointportions.

According to a first aspect of the present invention, there is provideda semiconductor apparatus comprising metal bumps formed so as to connectto a circuit pattern of a semiconductor device and a resin film formedon a circuit pattern forming surface of said semiconductor device so asto seal spaces between the metal bumps and become thinner than theheight of the metal bumps, the surfaces of the metal bumps projectingout from the resin film being cleaned.

Further, in the first aspect of the present invention, the surfaces ofthe metal bumps projecting out from the resin film are cleaned ofcomponents inviting a rise of a connection resistance and a drop in ajoint strength at least at connection interfaces.

Further, in the first aspect of the present invention, said metal bumpsare solder bumps and solder layers different in composition from saidsolder bumps are formed at the surfaces of the solder bumps projectingout from the resin film.

Further, in the first aspect of present invention, said solder bumps arecomprised of a high metal point solder and said solder layers arecomprised of a eutectic solder.

According to a second aspect of the present invention, there is provideda process of production of a semiconductor apparatus comprising a firststep of forming metal bumps so as to connect to a circuit pattern of asemiconductor device, a second step of forming a resin film on a circuitpattern forming surface of the semiconductor device so as to seal spacesbetween the metal spaces and to become thinner than a height of themetal bumps, and a third step of cleaning the surfaces of the metalbumps projecting out from the resin film.

Further, in the second aspect of the present invention, in said thirdstep, the surfaces are cleaned by removing components inviting a rise ina connection resistance and a decline in a joint strength at least at aconnection interface.

Further, in the second aspect of the present invention, in the thirdstep, the surfaces of the bumps are activated in parallel to thecleaning of the surfaces of the bumps.

Further, in the second aspect of the present invention, in the thirdstep, the resin film components deposited on the bumps are removed.

Further, in the second aspect of the present invention, in the thirdstep, oxides on the bump surfaces are removed.

Further, in the second aspect of the present invention, in the thirdstep, the cleaning of the surfaces of the bumps is performed by plasmacleaning

Further, in the second aspect of the present invention, the plasmacleaning is at least sputter etching by discharge plasma of an inertgas. Preferably, the plasma cleaning is at least oxygen plasma treatmentand then sputter etching by discharge plasma of an inert gas.

Preferably, the plasma cleaning is at least oxygen plasma treatment andthen sputter etching by discharge plasma of a reducing gas.

Further, in the second aspect of the present invention, in said thirdstep, the cleaning of the surfaces of the bumps is performed byirradiating a laser beam.

Further, in the second aspect of the present invention, in the thirdstep, the cleaning of the surfaces of the bumps is performed under areduced pressure atmosphere, an inert gas atmosphere, or a reducing gasatmosphere.

Further, in the second aspect of the present invention, in the thirdstep, the cleaning of the surfaces of the bumps is performed whileapplying a gas jet to the bumps to peel off the unnecessary componentswhich are then sucked away.

Further, in the second aspect of the present invention, preferably themetal bumps formed in the first step are solder bumps and, after thethird step, further there is provided a fourth step of forming solderlayers different in composition from the solder bumps on the surfaces ofthe solder bumps.

Further, preferably, the solder bumps are a high melting point solderand said solder layers are comprised of a eutectic solder.

Further, preferably, in the fourth step, the eutectic solder layers areformed by a printing method, plating method, or transfer method.

Further, in the second aspect of the present invention, the steps up toat least the third step are performed on a semiconductor device formedon a semiconductor substrate in a semiconductor wafer state.

Further, in the second aspect of the present invention, after the thirdstep, further there is provided a fourth step of cutting thesemiconductor wafer into unit semiconductor chips.

Further, in the second aspect of the present invention, after the stepof cutting the semiconductor wafer into unit semiconductor chips,further there is provided a step of mounting a semiconductor chip on amounting board from the bump forming surface side so as to connect it atthe bumps.

According to the present invention, the areas around the bases of therelatively weak strength metal bumps, for example, the areas around thespherical solder bumps, are reinforced by a resin. The thermal stress isrelieved by this resin.

Further, since the resin film is formed before the semiconductor deviceis mounted on the mounting board, so there is no need to inject thesealing resin between the mounting board and semiconductor device aftermounting the semiconductor device and therefore the productivity isimproved.

Further, since the resin film is formed with a height lower than theheight of the metal bumps, even if the semiconductor device is mountedon the mounting board, it will not contact the mounting board.

As a result, even if a defect occurs in a semiconductor device aftermounting, it becomes possible to easily remove the semiconductor devicefrom the mounting board.

Further, according to the present invention, the components inviting arise in a connection resistance and a decline in a joint strength atleast at a connection interface are removed from the surfaces of themetal bumps exposed from the resin film and the exposed surfaces arecleaned.

In this cleaning, for example, the resin film components deposited onthe bumps or the oxides at the surfaces of the bumps are removed.Further, the surfaces of the bumps are activated in parallel with thecleaning of the surfaces of the bumps.

Further, the surfaces of the metal bumps exposed from the resin film arecleaned by plasma cleaning. Therefore, the connection resistance isreduced and the joint strength increased when joining the metal bumps tothe lands of the mounting board or to the solder layers formed at thesurfaces of the bumps.

As a result, the thermal stress is relieved when mounting thesemiconductor device to the mounting board, the electricalcharacteristics are improved and the joint strength is increased whenthe semiconductor device is mounted to the mounting board, and therebymounting defects are reduced to a large extent.

Further, when the plasma cleaning is at least sputter etching by adischarge plasma of inert gas, by performing the sputter etching by RFdischarge plasma using for example Ar or another inert gas, the resinremaining on the surfaces of the metal bumps is removed by thesputtering and surfaces of clean metal bumps are exposed. Further,physical ion irradiation is used to chemically activate the surfacelayers.

By this, the surfaces of the metal bumps are cleaned, the connectionresistance at the time of joining them is reduced, and the jointstrength is increased, so the electrical characteristics when mounting asemiconductor device are improved.

Further, when the above-mentioned plasma cleaning is at least oxygenplasma treatment followed by sputter etching by discharge plasma of aninert gas, first oxygen plasma is used to burn off the resin remainingon the surfaces of the metal bumps by a reaction system comprised mainlyof a combustion reaction of the organic matter mainly comprising theresin and then using RF discharge plasma using Ar or another inert gasfor sputter etching and removal of the resin remaining on the surfacesof the metal bumps by sputtering.

In this case, compared with cleaning by only discharge plasma of aninert gas, two-stage plasma cleaning enables the residual resin to beeffectively removed by use of a chemical reaction (combustion reaction).

Further, the slight oxide films formed on the surfaces of the metalbumps during the cleaning by the oxygen plasma treatment are removed bythe Ar ions by sputtering.

Due to this, by cleaning the surfaces of the metal bumps more, theconnection resistance at the time of joining is reduced more and thejoint strength is increased more.

Further, when the above-mentioned plasma cleaning treatment is at leastoxygen plasma treatment and then sputter etching by discharge plasma ofa reducing gas, first oxygen plasma is used to burn off the resinremaining on the surfaces of the metal bumps, then HF or anotherreducing gas is used for sputter etching to more thoroughly remove theresin remaining on the surfaces of the metal bumps.

Due to this, the surfaces of the metal bumps are cleaned more, theconnection resistance at the time of joining is reduced more, and thejoint strength is increased more.

Therefore, compared with the case of plasma cleaning by only dischargeplasma of an inert gas or by discharge plasma by oxygen plasma and inertgas, the electrical characteristics at the time of mounting of thesemiconductor device are improved more.

Further, according to the present invention, the surfaces of the metalbumps exposed from the resin film are for example irradiated by a laserbeam etc. to cause extremely rapid heat expansion at the surface layersof the bumps and peel off the sealing resin components, then a gas jetis directed there to remove the same or the energy of a laser beam isused to reduce the surface layers of the bumps and naturally remove theoxides so as to clean and activate the surfaces of the bumps.

Further, by cleaning the surfaces of the bumps under a reducingatmosphere, an inert gas atmosphere, or a reducing gas atmosphere, it ispossible to suppress the progress of natural oxidation after thecleaning

Further, preferably, in the step of cleaning the surfaces of the bumps,gas is ejected from a gas ejection nozzle placed for example near thebumps under a reduced pressure atmosphere, inert gas atmosphere, orreducing gas atmosphere and a laser beam is irradiated to remove theresin coating components while applying suction to the areas near thebumps by the suction nozzle placed near the bumps.

Further, according to the present invention, by forming on the solderbumps comprised of for example a highly elastic high melting pointsolder used as the metal bumps solder layers different in compositionfrom the solder forming the solder bumps, preferably solder layerscomprised of a eutectic solder to be brought into contact with theeutectic solder precoated on the connection lands of the mounting board,the thermal stress is relieved by the elastic deformation of the abovehigh melting point solder even if thermal stress occurs caused by thedifference in coefficients of heat expansion between for example thesilicon chip constituting the semiconductor substrate of thesemiconductor device and the mounting board.

Further, by forming the solder layers by a eutectic solder, thewettability with the eutectic solder precoated on the connection landsof the mounting board becomes excellent and reliable joining bysoldering is achieved.

Further, since the surfaces of the solder bumps are cleaned by theplasma cleaning, the connection resistance is reduced and the jointstrength is increased at the joint portions of the solder bumps and thesolder layers.

Therefore, in the mounting of a semiconductor device to the mountingboard, the thermal stress is relieved and the connection resistance isreduced and joint strength increased, whereby mounting defects aregreatly reduced and the reliability of the joint portions by the metalbumps is improved.

Further, since the formation of the metal bumps and formation of theresin film and the plasma cleaning or laser beam irradiation and, insome cases, the formation of the solder layers are performed on asemiconductor device when at least three steps are performed on asemiconductor device formed on a semiconductor substrate in thesemiconductor wafer state, there is no need to perform this work on theindividual semiconductor devices, it is possible to perform this work ona large number of semiconductor devices at one time, and theproductivity is improved more.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of the present invention willbecome clearer from the following description of the preferredembodiments given with reference to the accompanying drawings, in which:

FIG. 1 is a sectional view of a semiconductor device according to anembodiment;

FIGS. 2A to 2C give sectional views of production steps of a process ofproduction of a semiconductor apparatus according to an embodiment,wherein FIG. 2A shows up to the step of opening the electrode pads, FIG.2B shows up to the step of forming the conductive film (BLM film), andFIG. 2C shows up to the step of removing the conductive film on theresist film by lift-off;

FIGS. 3A to 3C show the steps after FIGS. 2A to 2C, wherein FIG. 3Ashows up to the step of forming the surface protective film, FIG. 3Bshows up to the step of depositing the solder layer, and FIG. 3C showsup to the step of removing the solder layer on the resist film bylift-off;

FIGS. 4A to 4C show the steps after FIGS. 3A to 3C, wherein FIG. 4Ashows up to the step of forming the solder ball bumps by reflow, FIG. 4Bshows up to the step of forming the resin coating, and FIG. 4C shows upto the step of cleaning the surfaces of the bumps;

FIGS. 5A and 5B show the steps after FIGS. 4A to 4C, wherein FIG. 5Ashows up to the step of supplying the eutectic solder layers and FIG. 5Bshows up to the step of mounting on the mounting board;

FIG. 6 is a schematic sectional view of a first example of theconfiguration of a plasma treatment device for plasma cleaning in theprocess of production of FIG. 1;

FIG. 7 is a schematic sectional view of a second example of theconfiguration of a plasma treatment device for plasma cleaning in theprocess of production of FIG. 1;

FIG. 8 is a view for explaining a second embodiment of the process ofproduction of a semiconductor apparatus according to the presentinvention;

FIG. 9 is a schematic view of an excimer laser beam irradiation deviceaccording to a second embodiment;

FIG. 10 is a schematic view of an excimer laser beam irradiation deviceaccording to a second embodiment;

FIG. 11 is a sectional view of a semiconductor apparatus according to aprior art;

FIGS. 12A to 12C gives sectional views of production steps of a processof production of a semiconductor apparatus according to an example ofthe prior art, wherein FIG. 12A shows up to the step of forming aconductive film (BLM film), FIG. 12B shows up to the step of forming aresist film, and FIG. 12C shows up to the step of depositing the solderlayer; and

FIGS. 13A to 13B show the steps after FIGS. 12A to 12C, wherein FIG. 13Ashows the step up to the removal of the solder layer on a resist film bylift-off and FIG. 13B shows up to the step of forming solder ball bumpsby reflow.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Below, preferred embodiments of the present invention will be explainedin detail with reference to the drawings.

Note that the embodiments given below are preferred specific examples ofthe present invention, so technically preferable limitations are appliedto them, but the scope of the present invention is not limited so longas there is no particular express limitation of the present invention inthe following description. The invention is not limited to theseembodiments.

First Embodiment

FIG. 1 is a sectional view of a semiconductor apparatus produced by theprocess of production of a semiconductor apparatus according to thepresent embodiment.

The surface of the semiconductor chip 110 for forming the electrode pads111 comprised of aluminum etc. is for example covered by a surfaceprotective film 113 comprised of for example a silicon nitride layer orpolyimide layer, then electrode pad 111 portions are opened.

A conductive film 114 comprised of a stacked film of chrome, copper, andgold etc. is formed at the openings connected to the electrode pads 111.The conductive film is sometimes called a BLM (Ball Limiting Metal)film. Further, an upper surface protective film 115 comprised of forexample a polyimide is formed on the conductive film (BLM film) 114 andbump forming areas are opened.

In the above bump forming regions, bumps 116 b comprised of for examplehigh melting point solder balls are formed connected to the conductivefilm (BLM film) 114. Here, to avoid contact with the adjoining bumpsetc., the positions of formation of the bumps 116 b are shifted inaccordance with need with respect to the positions of formation of theelectrode pads 111 and the conductive film (BLM film) 114 is formed bypatterning so as to correspond to the same.

The surface of the semiconductor chip 110 (in actuality, the uppersurface protective film 115 etc.) at the spaces between the bumps 116 bis sealed by a resin film 117 comprised of an epoxy resin etc.

Further, the surfaces of the bumps 116 b exposed from the resin coating117 are cleaned for example by plasma cleaning.

A CSP type semiconductor chip 100 is constituted in this way.

On the other hand, the mounting board 200 is a board 210 comprised offor example a glass epoxy based material on the top of which areprovided lands (electrodes) 211 formed at positions corresponding to thepositions of formation of the solder bumps 116 b of the semiconductorchip 100 to be mounted and comprised of copper etc. and a not shownprinted circuit connected to the lands 211 and formed on the frontsurface or back surface or the two surfaces of the board 210. Thesurface of the board 210 other than the land 211 portions is covered bya solder resist 213.

The above CSP type semiconductor chip 100 is mounted on a mounting board200 with the bumps 116 b aligned with the lands 211. The bumps 116 b andlands 211 are mechanically and electrically connected by eutectic solderlayers 119.

The process of production of the above semiconductor apparatus will beexplained next with reference to the drawings.

First, as shown in FIG. 2A, electrode pads 111 comprised of an aluminumand copper alloy etc. are formed by patterning on a semiconductor wafer110 formed with circuit patterns of semiconductor chips by for examplethe sputtering method or etching etc., a surface protective film 113comprised of for example a silicon nitride layer or polyimide layer etc.is formed on top of it covering the entire surface, and electrode pad111 portions of the surface protective layer 113 are opened.

Next, as shown in FIG. 2B, a resist film R1 in which are opened regionsfor forming a conductive film connecting the electrode pads 111 andbumps formed in a later step are formed by patterning by aphotolithography step and a stacked film of chrome, copper, and gold isdeposited on the entire surface by for example the sputtering method toform a conductive film (BLM film) 114 so as to connect the electrodepads 111 in the pattern openings of the resist film R1. At this time, aconductive film 114 a is formed on top of the resist film R1.

Next, as shown in FIG. 2C, the resist film R1 is removed by lift-off tosimultaneously remove the conductive film 114 a formed on the resistfilm R1. Due to this, it is possible to leave only the conductive film(BLM film) formed in the pattern openings of the resist film R1.

Next, as shown in FIG. 3A, an upper surface protective film 115comprised of for example a polyimide layer etc. is formed on theconductive film (BLM film) 114 covering the entire surface and bumpforming regions of the upper surface protective film 115.

Next, as shown in FIG. 3B, a resist film R2 having pattern openings isformed by patterning at the bump forming regions by a photolithographystep.

Next, a solder layer is formed over the entire surface by for example avacuum evaporation method so as to form solder layers 116 in the patternopenings of the resist film R2. At this time, solder layers 116 a areformed over the resist film R2 as well.

Next, as shown in FIG. 3C, the solder layers 116 a formed over theresist film R2 are simultaneously removed by removing the resist film R2by lift-off. Due to this, it is possible to leave only the solder layers116 formed in the pattern openings of the resist film R2.

Next, as shown in FIG. 4A, heat treatment is performed to make thesolder layers 116 melt. These are cooled and solidified in a stateforming spheres due to the surface tension so as to form solder ballbumps 116 b comprised of high melting point solder balls.

Note that as the solder, a high melting point solder is used.

The high melting point solder is comprised of for example 97 percent orso of Pb and 3 percent or so of Sn. It has a high melting point and arelatively high elasticity.

Next, as shown in FIG. 4B, an epoxy-based resin is coated by a spin coatetc. at the semiconductor wafer level, then the resin is treated tocure, for example, is heat treated by curing at about 150° C. for about5 hours so as to cure the resin 117.

Due to this, a resin film 117 is formed at the bumps 116 b of thesemiconductor wafer 110 at a thickness forming a surface lower than theheight of the bumps 116 b while sealing the spaces between the bumps 116b.

At this time, resin coating components or oxides of the solder and otherinsulating impurities 117 a are formed on the surfaces of the bumps 116b depending on the process conditions of the resin coating step. In thedrawings, for convenience, a thickness greater than the actualinsulating impurities is shown.

Next, as shown in FIG. 4C, plasma cleaning is used to remove the resincoating components or oxides of the solder and other insulatingimpurities 117 a from the surfaces of the bumps 116 b to clean thesurfaces of the bumps 116 b projecting out from the surface of the resinfilm 117.

Here, the plasma cleaning is performed as explained later by the plasmatreatment device shown in FIG. 6 or FIG. 7 for example. By this, thesurfaces of the bumps 116 b are sputter etched and the resin coatingcomponents or oxides of the solder or other insulating impurities 117 aremaining at the surfaces are removed.

Next, as shown in FIG. 5A, eutectic solder layers 118 are formed by theprinting method, plating method, or transfer method connected to thebumps 116 b. By forming the eutectic solder layers 118, the height ofthe bumps is increased and the resistance to thermal stress is improved,the wettability with the solder at the time of mounting to the mountingboard can be improved, and the reliability of the connections can befurther improved.

Next, the semiconductor wafer 110 is cut along the cutting positions Dof the semiconductor wafer 110 by a dicing step to divide it intoindividual CSP type semiconductor chips 100.

Note that the above eutectic solder is comprised of for example 40percent or so of Pb and 60 percent or so of Sn. Compared with theabove-mentioned high melting point solder, it has a low melting point offor example not more than 200° C.

Heat treatment is applied at a temperature in a range where only theeutectic solder melts and the high melting point solder does not melt(for example, 200° C. to 250° C.), whereby the above eutectic solderfilm pattern melts and, as shown in FIG. 5A, forms balls and hardens bythe surface tension so as to join with the cleaned surfaces of the bumps116 b.

Due to this, solder bumps of a stacked structure of the bumps 116 b andeutectic solder 118 are formed.

Next, as shown in FIG. 5B, the CSP type semiconductor chip 100 ismounted on a mounting board 200 from the bump 116 b forming surface.

The mounting board 200 is a board 210 comprised of for example a glassepoxy based material on the top of which are provided lands (electrodes)211 formed at positions corresponding to the positions of formation ofthe solder bumps 116 b of the semiconductor chip 100 to be mounted andcomprised of copper etc. and a not shown printed circuit connected tothe lands 211 and formed on the front surface or back surface or the twosurfaces of the board 210.

A precoated solder layer 212 comprised of a eutectic solder is formed onthe lands 211. Further, the surface of the board 210 other than the land211 portions is covered by a solder resist 213.

The above CSP type semiconductor chip 100 is mounted on the abovemounting board 200 with the bumps 116 b aligned with the lands 211. Heattreatment of for example 200 to 250° C. is used to make the eutecticsolder layer 118 or precoated solder layer 212 reflow without the bumps116 b melting, eutectic solder layers 119 are formed at the jointpositions of the bumps 116 b and lands 211, and the CSP typesemiconductor chip 100 and mounting board 200 are mechanically andelectrically connected to produce the semiconductor device shown in FIG.1.

In this case, since the eutectic solder 118 is comprised by a eutecticsolder film, the wettability of the eutectic solder 118 and the eutecticsolder film 212 prepared on the lands 211 is excellent. Therefore, theeutectic solder 118 and the lands 211 join strongly with each other dueto their close affinity, so the soldering is reliable.

Next, two examples of the above-mentioned plasma cleaning will beexplained with reference to FIG. 6 and FIG. 7.

First, in a first embodiment of the plasma cleaning, the plasmatreatment device shown in FIG. 6 is used for plasma cleaning by adischarge plasma of an inert gas, for example, argon gas.

In FIG. 6, the plasma treatment device 300 is a so-called triode type RFplasma treatment device comprised of a sealed plasma treatment chamber301, a anode plate 302 provided at the top inside the plasma treatmentchamber 301, a stage 303 serving as a cathode plate provided at thebottom, a lattice electrode 304 provided between the anode plate 302 andthe stage 303, a coupling capacitor 305 through which a plasmageneration power source 306 is connected to the cathode plate 302, and acoupling capacitor 307 through which a substrate bias power source 308is connected to the stage 303.

According to the plasma treatment device 300 of this configuration, atreated substrate, that is, the semiconductor wafer 110, is placed onthe stage 303, a bias voltage is applied between the stage 303 andlattice electrode 304 by the substrate bias power source 308 in thestate with for example an argon gas introduced inside as an inert gas,and the plasma generation power source 306 is used to apply a plasmasource power between the anode plate 302 and the lattice electrode 304.

Due to this, a discharge plasma 309 of argon gas is produced between theanode plate 302 and the lattice electrode 304, and argon ions Ar+ flyout from the anode plate 302 toward the lattice electrode 304, passthrough the lattice electrode 304, and strike the semiconductor wafer110 on the stage 302.

Therefore, due to the sputtering action, the surface of thesemiconductor wafer 110, that is, the surface of the resin 117 and theprojecting surfaces of the bumps 116 b are etched, whereby the resin 117a remaining on the surfaces of the bumps 116 b is removed.

In this case, the operating conditions of the above plasma treatmentdevice 300 are set as shown below for example. That is,

Flow rate of argon gas: 25 sccm

Temperature of stage 303: Room temperature

Plasma source power: 700W (2 MHZ)

Substrate bias voltage: 350V (13.56 MHZ)

Treatment time: 120 seconds

When the plasma cleaning of the semiconductor wafer 110 was performed bythese operating conditions, due to the sputtering action of the Ar+ions, the resin 117 a remaining on the surfaces of the bumps 116 b waseffectively removed and the surfaces of the bumps 116 b were cleaned.

Next, an explanation will be made of a second example of the plasmacleaning.

In the second example, the plasma treatment device shown in FIG. 7 wasused for oxygen plasma treatment, then discharge plasma of a reducinggas was used for plasma cleaning.

In FIG. 7, the plasma treatment device 400 is an ICP (InductivelyCoupled Plasma) high density plasma treatment device of a knownconfiguration comprised of a sealed plasma treatment chamber 401, ananode plate 402 provided at the top inside the plasma treatment chamber401, a vertically movable stage 403 serving as a cathode plate providedat the bottom, an inductively coupled coil 404 provided around theplasma treatment chamber 401, a coupling capacitor 405 through which asubstrate bias power source 406 is connected to the stage 403, and anICP power source 407 connected to the inductively coupled coil 404.

According to the plasma treatment device 400 of this configuration, atreated substrate, that is, the semiconductor wafer 110, is placed onthe stage 403, a bias voltage is applied between the stage 403 and anodeelectrode 402 by the substrate bias power source 406 in the state withoxygen gas introduced inside, and a high frequency induction field isproduced inside the plasma treatment chamber 401.

Due to this, the electrons inside the plasma treatment chamber 401 areaccelerated, a high density oxygen plasma 408 is produced, and oxygenions strike the semiconductor wafer 110 on the stage 403.

Therefore, due to the plasma ashing action, the surface of thesemiconductor wafer 110, that is, the surface of the resin 117 and theprojecting surfaces of the bumps 116 b, are etched, whereby the resincoating components or oxides of the solder or other insulatingimpurities 117 a remaining on the surfaces of the bumps 116 b areremoved.

In this case, the operating conditions of the above plasma treatmentdevice 400 are set as shown below for example. That is,

Flow rate of oxygen gas: 50 sccm

Pressure: 0.3 Pa

Temperature of stage 403: 90° C.

Power of ICP power source: 1000W (450 kHz)

Substrate bias voltage: 100V (13.56 MHZ)

Treatment time: 20 seconds

When the plasma cleaning of the semiconductor wafer 110 is performed bythese operating conditions, due to the ashing action of the oxygenplasma, the resin 117 a remaining on the surfaces of the bumps 116 b iseffectively removed.

Note that in this case, the surfaces of the bumps 116 b are slightlyoxidized by the oxygen plasma and an oxide film is formed.

Next, plasma etching is performed by reducing gas to remove the oxidefilm of the bumps 116 b.

This reducing gas plasma etching is performed in the above plasmatreatment device 400 by changing the settings of the operatingconditions, introducing a mixed gas of for example hydrofluoride (HF)gas as the reducing gas and for example argon gas as the inert gasinside the plasma treatment chamber 400, and etching the surfaces of thebumps 116 b by the plasma etching action of the reducing gas.

In this case, the operating conditions of the above plasma treatmentdevice 400 are set as shown below for example. That is,

Flow rate of HF gas: 25 sccm

Flow rate of argon gas: 25 sccm

Pressure: 0.13 Pa

Temperature of stage 403: 90° C.

Power of ICP power source: 1000W (450 kHz)

Substrate bias voltage: 250V (13.56 MHZ)

Treatment time: 20 seconds

When the plasma cleaning of the semiconductor wafer 110 is performed bythese operating conditions, the oxide film formed on the surfaces of thebumps 116 b is reduced by the reaction with the HF gas and thesputtering action of the Ar+ ions causes sputter removal and cleans thesurfaces of the bumps 116 b.

A high density plasma generation source is used by the plasma treatmentdevice 400 and treatment in a low pressure atmosphere is enabled bythis. Due to this, the ion species produced in large quantities strikethe surface of the semiconductor chip 110 substantially perpendicularlywithout scattering and the etching by the sputtering by irradiation ofAr+ ions is performed at a high speed with good efficiency.

Therefore, even if the substrate bias voltage is set low so as to reducethe damage caused by the plasma cleaning of the semiconductor chip 110,the time required for the plasma cleaning of the surfaces of the bumps116 b is shortened without a reduction in the etching rate.

Therefore, the resin 117 a remaining on the surfaces of the bumps 116 bare more effectively removed by the plasma etching by the oxygen plasmaand the plasma etching by the reducing gas and the surfaces are cleanedmore.

Further, in the above example, hydrofluoride gas HF was used as thereducing gas, but the invention is not limited to this. For example, itis clear that it is also possible to use for example hydrogen gas H₂ orhydrochloride gas HCl or another reducing gas.

Here, when a liquid form of HF or HCl etc., for example bubbling usinghelium He or another carrier gas, heating aeration, ultrasonic aeration,or another suitable means is used to introduce it into the plasmatreatment chamber 301, 401.

Further, in the above examples, a triode-type RF plasma treatment device300 or ICP high density plasma treatment device 400 was used for theplasma cleaning of the surfaces of the bumps 116, but the invention isnot limited to this. For example, it is clear that it is also possibleto use a parallel plate type RF plasma treatment device or a so-calledTCP, ECR, helicon wave plasma, or other type of high density plasmatreatment device.

As explained above, according to the first embodiment, the bases of thebumps are reinforced by a resin film sealing the spaces between thebumps, it is possible to increase the resistance to heat expansionstress and improve the connection reliability even without completelysealing the area between the semiconductor chips and the mounting boardby a resin, the detachment of a CSP type semiconductor chip from themounting board is easy, and it is possible to simply replace defectivecomponents (rework).

Further, the bumps 116 b are secured and held by the resin film 117.Even if thermal stress occurs between the semiconductor substrate andthe mounting board due to changes in temperature of the surroundingsetc. after mounting, since the solder bumps are secured by the resinfilm 117 and the bumps 116 b have elasticity, the resin film 117 as awhole receives the thermal stress and the bumps 116 b elastically deformso the thermal stress is relieved. Due to this, breakage of the jointportions of the solder bumps 23 by thermal stress is prevented and thereliability of the solder bumps is improved.

Further, since the resin film 117 is formed on the surface of theelectrode pad 111 side of the semiconductor chip 100 before mounting tothe mounting board 200, the resin film 117 never contacts the surface ofthe mounting board 200.

Therefore, there is no need to inject resin between the semiconductorchips 100 and the mounting board 200 as in the past, so even whenreducing the pitch of semiconductor chips 100, since the sealing resin117 reliably covers the entire surface of the semiconductor wafer, thethermal stress is reliably relieved and the durability with respect tothermal stress is improved.

Further, the bumps 116 b are surrounded by the resin film 117, then theexposed surfaces projecting out from the resin film 117 are cleaned byplasma cleaning Further, a eutectic solder 118 is formed on the cleanedsurfaces, so the connection resistance at the interface of the bumps 116b and the eutectic solder 118 is reduced and the joint strength isincreased.

Therefore, bumps are comprised with lower resistances and higher jointstrengths and the occurrence of mounting defects is reduced more.

Therefore, according to the present embodiment, the electricalcharacteristics and the bonding strength at the interfaces are improved,whereby the reliability and durability of the semiconductor chip 100 andthe various equipment in which it is installed are greatly improved.

In the above embodiments, the bumps 116 b are covered by a film byvacuum evaporation and a pattern formed by lift-off of the photoresist,but the invention is not limited to this. It is clear thatelectroplating etc. may also be used to form it.

Further, in the above-mentioned embodiment, the explanation was given ofthe case of forming solder bumps with respect to the electrode pads 111of a semiconductor device, but the invention is not limited to this. Itis clear that the present invention may also be applied to the case offorming solder bumps with respect to other types of semiconductordevices.

Further, in the embodiment explained above, the explanation was given ofthe example of use, as a solder, of a high melting point soldercomprised of for example 97 percent or so of Pb (lead) and 3 percent orso of Sn or a eutectic solder comprised of for example 40 percent or soof Pb and 60 percent or so of Sn, but of course it is also possible touse another solder not containing Pb, for example, a solder comprised of96.5 percent of tin and 3.5 percent of silver, a solder comprised of99.3 percent of tin and 0.7 percent or copper, etc.

Further, in the above embodiment, the explanation was given of theexample of ball-shaped bumps comprised of solder as the bumps, but thepresent invention is not limited to this. For example, of course, it isalso possible to use copper ball bumps, nickel ball bumps, or othertypes of metal bumps.

Second Embodiment

FIG. 8 is a view for explaining a second embodiment of the process ofproduction of a semiconductor apparatus according to the presentinvention.

The point of difference of the second embodiment from the firstembodiment explained above is that the cleaning of the surfaces of thebumps 116 b exposed from the resin film 117 is performed by removing theresin film and other unnecessary components by irradiation of a laserbeam L as shown in FIG. 8 instead of plasma cleaning.

The processing of the rest of the steps is performed in the same way asthe first embodiment. That is, in the second embodiment, the step shownin FIG. 8 is performed instead of the step of FIG. 4C in the process ofproduction explained with relation to FIGS. 2A, 2B, and 2C, FIGS. 3A,3B, and 3C, FIGS. 4A, 4B, and 4C, and FIGS. 5A and 5B.

Further, since a semiconductor apparatus similar to the semiconductorapparatus shown in FIG. 1 is obtained by this process of production, adetailed explanation will be given below of the cleaning by thisirradiation of a laser beam.

Specifically, a resin film 117 is formed on the surface of thesemiconductor wafer 110 for forming the bumps 116 b to a thickness forforming a surface lower than the height of the bumps 116 b, then, asshown in FIG. 8, an excimer laser beam L is irradiated on the surface ofthe semiconductor wafer 110 forming the bumps 116 b to remove from thesurfaces of the bumps 116 b the resin film components or oxides of thesolder or other insulating impurities 117 a and clean the surfaces ofthe bumps 116 b projecting out from the surface of the resin film 117.

Here, the laser beam may be irradiated from a laser beam irradiationdevice such as shown in the schematic view of FIG. 9 for example.

The laser beam irradiation device 500 is provided with a wafer stage501, a not shown light source for irradiating an excimer laser beam L, agas ejection nozzle 504 for ejecting a gas 505, and a suction nozzle506.

In the laser beam irradiation device 500, the semiconductor wafer 502for processing is placed on and secured to the wafer stage 501 with thebump forming surface facing upward and a KrF excimer laser beam L withfor example a wavelength of 248 nm, an energy density of 400 mJ/cm², anda pulse oscillation of 30 Hz is irradiated on the bump forming surfaceof the semiconductor wafer to sweep it at a speed of 50 mm/sec.

At this time, the nitrogen gas or other gas 505 is ejected from the gasejection nozzle 504 provided at the laser beam irradiation device to thebump forming surface at a flow rate of 20 l/sec to peel off the sealingresin components and other insulating impurities 117 a which are thensucked away by the suction nozzle 506.

Note that the movement of the wafer stage 501 and laser pulses aresynchronized and a laser beam irradiated at a constant overlap. Theamount of irradiation of the laser beam is controlled to be uniform inthe plane of the semiconductor wafer.

Due to the above irradiation of a laser beam, extremely sharp heatexpansion is caused at the surface portions of the bumps 116 b, thesealing resin components deposited on the surfaces of the bumps 116 bare peeled off, and a gas jet is applied to remove them so as to cleanthe surfaces of the bumps. Further, the energy of the laser beam may beused to reduce the surface portions of the bumps and remove the naturaloxides and activate the surfaces of the bumps.

Further, the laser beam may be irradiated by a laser beam irradiationdevice such as shown in the schematic view of FIG. 10 for example.

The laser beam irradiation device 500A is provided with a wafer cassette508 in which untreated wafers 502 are housed, a reaction treatmentchamber 507, and a load-lock chamber 510 in which treated wafers 502 arehoused. The wafer cassette 508 and reaction treatment chamber 507 andthe reaction treatment chamber 507 and load-lock chamber 500 areconnected by gate valves 509.

In the reaction treatment chamber 507, the laser beam irradiation device500A is provided with a wafer stage 501, a not shown light source forirradiating the excimer laser beam L, a gas ejection nozzle 504 forejecting a gas 505, and a suction nozzle 506.

Further, the reaction treatment chamber 507 is provided with a gasexhaust port 512 connecting the gas introduction port 511 to a not shownsuction pump. The inside of the reaction treatment chamber 507 can bemade a reduced pressure atmosphere, an inert gas atmosphere, or areducing gas atmosphere.

In the above laser beam irradiation device 500A, the air is exhaustedfrom the gas exhaust port 512 to reduce the pressure, a nitrogen gas isintroduced from the gas introduction port 511, and a not shown waferoperating mechanism is used to take out a semiconductor wafer to betreated from the wafer cassette in the reaction treatment chamber 507controlled to a 1 Torr nitrogen atmosphere and to place and secure thebump forming surface on the wafer stage 501 facing upward.

A KrF excimer laser beam L with for example a wavelength of 248 nm, anenergy density of 400 mJ/cm², and a pulse oscillation of 30 Hz isirradiated on the bump forming surface of the semiconductor wafer tosweep it at a speed of 50 mm/sec.

At this time, the nitrogen gas or other gas 505 is ejected from the gasejection nozzle 504 provided at the laser beam irradiation device to thebump forming surface at a flow rate of 20 l/sec to peel off the sealingresin components and other insulating impurities 117 a which are thensucked away by the suction nozzle 506.

The treated semiconductor wafer 502 is housed in the load-lock chamber510 by a not shown wafer operating mechanism.

Note that the movement of the wafer stage 501 and laser pulses aresynchronized and a laser beam irradiated at a constant overlap. Theamount of irradiation of the laser beam is controlled to be uniform inthe plane of the semiconductor wafer.

Due to the above irradiation of a laser beam, the sealing resincomponents deposited on the surfaces of the bumps 116 b are peeled offand a gas jet is applied to remove them so as to clean the surfaces ofthe bumps. Further, it is possible to remove the natural oxides on thesurfaces of the bumps and activate the surfaces of the bumps.

Further, by performing the above treatment in a reduced pressureatmosphere, inert gas atmosphere, or reducing gas atmosphere, the oxygenis removed from the reaction treatment chamber 507. The chamber becomesa high temperature by the cleaning by irradiation of a laser beam andthe progress of natural oxidation of the activated surfaces of the bumpscan be suppressed.

Next, as shown in FIG. 5A, a eutectic solder layer 118 is formedconnected to the bumps 116 a by the printing method, plating method, ortransfer method, then the semiconductor wafer 110 is cut along thecutting positions D of the semiconductor wafer 110 by a dicing step todivide it into individual CSP type semiconductor chips 100.

Further, as shown in FIG. 5B, a CSP type semiconductor chip 100 ismounted on the mounting board 200 from the bump 116 b forming surface.

In the second embodiment, in the same way as the semiconductor apparatusaccording to the first embodiment explained above, the bases of thebumps are reinforced by the resin film sealing the spaces between thebumps. Even if the area between the semiconductor chips and the mountingboard is not completely sealed by the resin, it is possible to increasethe resistance to heat expansion stress and improve the connectionreliability, the removal of a CSP type semiconductor chip from themounting board is easy, and the work of replacement of defectivecomponents (rework) is simple.

Further, according to the process of production of a semiconductorapparatus of the present embodiment, irradiation by a laser beam etc. isused to cause extremely sharp heat expansion at the surface portions ofthe bumps to peel off the sealing resin components which are thenremoved by a gas jet or the energy of the laser beam is used to reducethe surface layer portions of the bumps and remove the natural oxides soas to clean and activate the surfaces of the bumps before mounting, so arise in the electrical resistance and a decline in the joint strength atthe bump joint interfaces are suppressed and the connection reliabilitycan be improved.

Further, in the same way as the above first embodiment, as thesemiconductor apparatus produced by the second embodiment, any of a MOStransistor type semiconductor apparatus, bipolar type semiconductorapparatus, BiCMOS type semiconductor apparatus, semiconductor apparatuscarrying logics and memories, and other semiconductor apparatuses may beapplied.

Further, the process of production of a semiconductor apparatus is notlimited to the above second embodiment.

For example, the configuration of the laser beam treatment device,conditions of the processes, structure of the wafer, etc. are notlimited to the details explained in the above embodiments.

Further, the bumps may be formed on the wafer by use of transfer of thesolder balls and other various methods.

In addition, various changes may be made within the scope of the gist ofthe present invention.

As explained above, according to the present invention, it is possibleto reliably relieve the thermal stress between a semiconductor deviceand mounting base without the use of a sealing resin and possible toreduce the connection resistance and increase the strength of the jointportion.

Further, according to the present invention, when using the process ofreinforcing the bases of the bumps by a resin film sealing the spacesbetween bumps, it is possible to suppress the rise of the electricalresistance and decline of the joint strength at the bump jointinterfaces and improve the connection reliability.

While the invention has been described with reference to specificembodiment chosen for purpose of illustration, it should be apparentthat numerous modifications could be made thereto by those skilled inthe art without departing from the basic concept and scope of theinvention.

1. A method of producing a semiconductor apparatus, the methodcomprising the steps of: forming metal ball bumps in direct contact witha circuit pattern of a semiconductor device formed on a semiconductorsubstrate in a semiconductor wafer state; forming a resin film on acircuit pattern forming surface of said semiconductor device so as toseal spaces between said metal ball bumps and to become thinner than aheight of the metal ball bumps; cleaning the surfaces of the metal ballbumps projecting out from the resin film using plasma cleaning such thatthe surfaces are cleaned by removing components inviting a rise in aconnection resistance and a decline in a joint strength at least at aconnection interface; after the cleaning step, forming eutectic solderlayers different in composition from the metal ball bumps on thesurfaces of the metal ball bumps; after the forming solder layers step,cutting the semiconductor substrate into unit semiconductor chips, eachsemiconductor chip having at least one of said semiconductor device; andafter the cutting step, mounting at least one of the semiconductor chipson a mounting board from a bump forming surface side of thesemiconductor chip so as to connect the eutectic solder layers of thesemiconductor chip to the mounting board with the resin film directlycontacting the semiconductor chip and not directly contacting themounting board.
 2. A process of production of the semiconductorapparatus as set forth in claim 1, wherein, in said cleaning step, anyresin film components deposited on said bumps are removed.
 3. A processof production of a semiconductor apparatus as set forth in claim 1,wherein, in said cleaning step, oxides on said bump surfaces areremoved.
 4. A process of production of a semiconductor apparatus as setforth in claim 1, wherein, in said cleaning step, the cleaning of thesurfaces of the bumps is performed by plasma cleaning.
 5. A process ofproduction of a semiconductor apparatus as set forth in claim 4, whereinsaid plasma cleaning is at least sputter etching by discharge plasma ofan inert gas.
 6. A process of production of a semiconductor apparatus asset forth in claim 4, wherein said plasma cleaning is at least oxygenplasma treatment and then sputter etching by discharge plasma of aninert gas.
 7. A process of production of a semiconductor apparatus asset forth in claim 4, wherein said plasma cleaning is at least oxygenplasma treatment and then sputter etching by discharge plasma of areducing gas.
 8. A process of production of a semiconductor apparatus asset forth in claim 1, wherein, in said cleaning step, the cleaning ofthe surfaces of the bumps is performed by irradiating a laser beam.
 9. Aprocess of production of a semiconductor apparatus as set forth in claim1, wherein, in said cleaning step, the cleaning of the surfaces of thebumps is performed under a reduced pressure atmosphere, an inert gasatmosphere, or a reducing gas atmosphere.
 10. A process of production ofa semiconductor apparatus as set forth in claim 1, wherein, in saidcleaning step, the cleaning of the surfaces of the bumps is performedwhile applying a gas jet to the bumps to peel off the unnecessarycomponents which are then sucked away.
 11. A process of production of asemiconductor apparatus as set forth in claim 1, wherein the metal ballbumps formed in the first step are solder bumps.
 12. A process ofproduction of a semiconductor apparatus as set forth in claim 11,wherein said solder bumps have a melting point higher than a meltingpoint of said eutectic solder layers and said eutectic solder layers arecomprised of a eutectic solder.
 13. A process of production of asemiconductor apparatus as set forth in claim 12, wherein, in saidforming solder layers step, the eutectic solder layers are formed by aprinting method, plating method, or transfer method.